In production of a roll of labels (pressure-sensitive labels), just printing label images by a label printing device on a face of label material provided in roll form (a roll or continuous label stock), is not enough to obtain an end product. To provide an end product, the label printing device cooperates with a finisher, to cause the finisher to perform a process to cut label images printed on the face of a continuous label stock into label shapes with a cutting tool or die (referred to as die-cutting) and a process to remove waste or waste face material surrounding the labels from the continuous label stock (referred to as removing waste). In order to allow a finisher to perform appropriate processing on a continuous label stock in the above processes, a label printing device prints reference marks, so-called “eye marks”, which are marks to tell the finisher where to cut a face of the continuous label stock, together with label images on the face of the continuous label stock. The finisher then die-cuts the label images printed on the continuous label stock into label shapes, while sensing the reference marks.
As an example of a technique of label printing, Japanese Unexamined Patent Publication (JP-A) No. 2017-062536 discloses a label-printing control apparatus which instructs a label printing device to print label images on label material on which the label images are to be cut into label shapes by a die-culling machine. The label-printing control apparatus comprises the following built-in controller. The built-in controller performs print-data analysis by obtaining print data including one or more label images and corresponding one or more cut marks each indicating a contour to cut the corresponding label image printed on label material, and by extracting the one or more cut marks from the print data. The built-in controller then creates an end product image by removing the one or more cut marks from the print data. The built-in controller finds an apex of each cut mark, and creates an adjusting image including a plurality of the cut marks with graduations added adjacent to the apex of each cut mark. The built-in controller then outputs image data of the end product image and the adjusting image to the label printing device and instructs the label printing device to print the end product image and the adjusting image successively on label material.
As another example of a technique of label printing, JP-A No. 2016-087902 discloses a method for adjusting cutting positions to printing positions in label printing. The method comprises a process of using an ink-jet head that discharges an ink on a medium for printing, to print an origin-point adjusting image having a plurality of checking blocks on the medium. The method further comprises a process of culling the medium with a cutting head along the contour of the origin-point adjusting image. The method further comprises a process of removing a part of the medium cut by the cutting head from the medium; and a process of inputting the amount of displacement between the printing position of the ink-jet head on the medium and the cutting position of the cutting head on the medium to a controller that controls the inkjet head and the cutting head, so as to be used for a value of correction between the printing position of the ink-jet head and the cutting position of the cutting head. The method further comprises a check process to be performed, while printing on the medium the origin-point adjusting image or cutting the medium. The check process is performed by displacing the position of printing with the ink-jet head or the position of cutting with the cutting head, by a certain shift amount at each of the plurality of checking blocks, in the main-scanning direction or the sub-scanning direction of the ink-jet head.
By using reference marks printed on a face of a label stock, a finisher can determine cutting positions on the label stock. Since finishers are configured to perform cutting with a cutting tool (die), which is mounted to the finisher so as to cut out a label shape, the mounted die can be misaligned and be out of its proper position. In view of that, in a general die-cutting process, after a finisher cuts a predetermined number of label images printed on a label stock into label shapes with the die, an operator checks the label images cut with the die visually and adjusts the die-cutting positions. This position adjustment is repeated until the die becomes to cut printed label images at desired positions on the label stock. It needs the label printing device to print more than a number of label images ordered by a customer. It further needs an unskilled operator to perform the position adjustment repeatedly until the operator gets skilled at the position adjustment, because the accuracy of the position adjustment depends on the operator's skill. It can result in a problem that it is necessary for the label printing device to print a large number of label images which will be wasted for the position adjustment, and resources and man-hours are wastefully used for the position adjustment.
In view of that. JP-A No. 2017-062536 discloses a technique to use graduations (a scale) printed adjacent to an apex of each cut mark, to allow an operator to recognize the amount of displacement of die-cutting positions from printing positions. In this technique, scales are spaced apart from respective reference marks with fixed spaces on the face of a label stock. It results in that the same part of the scale remains on every label given after die-cutting of the label stock. Therefore, an operator hardly recognizes the amount of displacement of the die-cutting positions from the printing positions intuitively from graduations of the scale remaining on each label. IP-A No. 2016-087902 discloses a technique to use an origin-point adjusting image having a plurality of checking blocks, to perform printing the origin-point adjusting image or cutting the contour of the origin-point adjusting image printed on a label stock, while displacing the printing position or the cutting position by a certain shift amount at each of the checking blocks. In this technique, the positional relationship between the printing position of the contour of each checking block and the corresponding cutting position is merely changed gradually along the origin-point adjusting image. With this technique, an operator hardly recognizes the accurate amount of displacement of the cutting positions from the printing positions.